JP3418061B2 - Video signal processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to signal processing of color television signals, and more particularly to a video signal processing device having a filter automatically adjusted.

[0002]

2. Description of the Related Art Conventionally, as a method for improving the image quality of a VTR, there is a technique disclosed in Japanese Patent Publication No. 6-083464. This technique uses cascaded first to third equalizers and two subtractors to extract the chroma difference, and sets the group delay amount of the second and third equalizers to be smaller than that of the first equalizer. Since the color contour signal for performing the logical operation with the luminance contour signal and the color contour signal for multiplying the signal obtained as a result of the logical operation have different modes, these equalizers require high-precision characteristics. To be done. In this technology, when the image quality improving device is integrated into an IC, it is difficult to integrate a high-precision equalizer in consideration of variations in integrated elements in the manufacturing process and ratio accuracy between elements. Then, an external block filter was used as a filter element. Further, desired characteristics have been secured by adjusting a block filter provided outside the IC.

[0003]

The image quality improving apparatus using the above-described technique has a problem that the cost is increased and the board area is increased because a block filter is used as an external component. Further, this technique has a problem in that the operator has to adjust the equalizer, which complicates the manufacturing process and increases the cost. In addition, in this technique, since the image quality improving device is composed of two elements, that is, the IC and the block filter, there is a problem that the temperature characteristics of the respective elements are different and it is not possible to cope with the temperature change after the adjustment. The present invention solves the above problems, and an object of the present invention is to provide a video signal processing apparatus in which the equalizer is built-in and a low-cost and highly-accurate filter capable of performing automatic adjustment is integrated.

[0004]

In order to solve the above-mentioned conventional problems and achieve the above object, the present invention has the following constitution. The present invention relates to an image signal processing device that performs signal processing by separating a video signal into a luminance signal and a color signal, and an equalizer that delays the color signal and a second-order low-pass filter (hereinafter referred to as LPF) that delays the color signal. ), A phase detector to which the output of the equalizer and the output of the second-order low-pass filter are input, and the phase difference between the two inputs of the phase detector is set to 90 degrees, The output signal of the detector is used to feedback-control the equalizer and the second-order low-pass filter to automatically adjust the phase delay amounts of the equalizer and the second-order low-pass filter, thereby integrating a highly accurate filter. did.

Further, according to the present invention, in a video signal processing device for separating a video signal into a luminance signal and a chrominance signal for signal processing, a first equalizer and a second equalizer in which equalizers for delaying the chrominance signal are connected in cascade. And an equalizer, and a second-order LPF for delaying a color signal, an output of the equalizer and the 2LP.
A phase detector to which the output of F is input, and a first color contour signal creating means for creating a color contour signal using the input signal of the first equalizer and the output signal of the second equalizer; Second color contour signal creating means for creating a color contour addition signal using the output signal of the first equalizer and the output signal of the third equalizer, and luminance for creating a luminance contour signal from the luminance signal separated from the video signal. Contour signal creating means, comparing means for comparing the output of the first color contour signal creating means with the output of the luminance contour signal creating means, and output of the second color contour signal creating means and output of the comparing means. And a adding means for adding the color contour addition signal to the output signal of the second equalizer to obtain a contour-enhanced color signal. Using the output signal 1, the second, with a configuration that feedback controls the third equalizer and secondary LPF, integrated high-precision filter.

Further, according to the present invention, in the video signal processing device, the first, second, and third variable amplifier circuits are connected to the outputs of the first, second, and third equalizers, respectively, and the first and second variable amplifier circuits are connected. Level detecting means for comparing the level of the input signal of the equalizer with the level of the output signal of the third variable amplifier circuit is provided, and the output of the amplified equalizer is used as a part of the input signal of the phase detector, The variable amplifier circuit is feedback-controlled by using the output signal of the level detection means so as to automatically adjust the variation in the output level of the equalizer, whereby a highly accurate filter is integrated.

According to the present invention, in a video signal processing device for separating a video signal into a luminance signal and a color signal and performing signal processing, an equalizer for delaying the color signal, a variable amplifier circuit connected to the output of the equalizer, Secondary L that delays the color signal
PF, a phase detector to which the output of the equalizer and the output of the 2LPF are input, and level detection means for comparing the level of the input signal of the equalizer and the level of the output signal of the variable amplifier circuit are provided, and the phase detector The phase difference between the two inputs of the detector is set to 90 degrees, the output of the amplified equalizer is used as a part of the input signal of the phase detector, and the output signal of the level detecting means is used to The variable amplifier circuit is feedback-controlled to automatically adjust the variation of the output level of the equalizer, so that a highly accurate filter is integrated.

Further, according to the present invention, in all of the above inventions, the output signal of the phase detector is used to perform feedback control of at least one filter used in the video signal processing device, thereby achieving high precision. Integrated filter.

According to the present invention, in the above invention, a circuit for extracting a burst signal from the composite synchronizing signal is provided, and the phase detector is configured to operate in synchronization with the burst period, and the phase detector uses only the burst signal. And the output signal of the phase detector is used to operate the equalizer and the second-order LP.
Feedback control was performed on F to integrate a filter with higher accuracy.

Further, in the present invention according to the above-mentioned invention, the phase detector is configured to operate during a vertical synchronizing period, the phase detector is operated only during the vertical synchronizing period, and the output signal of the phase detector is used. The equalizer and the secondary LPF
Feedback control was performed to integrate a filter with higher accuracy.

According to the present invention, in the video signal processing apparatus having the above structure, a switching circuit for switching the color signal and the reference signal to the input of the equalizer, and a reference for removing the reference signal added to the color signal at the output of the equalizer. A signal removing circuit is provided, a reference signal is mixed with the color signal, the phase detector and the reference signal removing circuit are operated in synchronization with the reference signal, and the equalizer and the secondary LPF are output by using the output signal of the phase detector. Feedback control.

According to the present invention, in the above video signal processing device, a color subcarrier (hereinafter referred to as fsc) is added to the reference signal.
A video signal processing device having a structure that does not depend on the content of a color signal is provided by using.

According to the present invention, in the above video signal processing device, the level detection means is composed of at least two multipliers and one subtractor, and the level of the variable amplification circuit is automatically adjusted.

According to the present invention, in the above video signal processing device, the means for feedback controlling the equalizer and the secondary LPF is provided with two or more voltage-current converters which can be switched by a mode switching signal, for example, NTSC. Supports both signal system and PAL system.

Further, in the present invention, in the above video signal processing device, the means for feedback controlling the equalizer and the secondary LPF has a phase difference between two inputs of a phase detector of 90 ± 90.
A voltage-current converter that does not change more than once
It is possible to correct manufacturing variations when filters are integrated,
Enabled to stabilize the characteristics.

According to the present invention, an automatic gain control circuit (hereinafter referred to as an AGC circuit) for removing a level fluctuation of a video signal, a first LPF for separating a luminance signal from the video signal, and a frequency by emphasizing the luminance signal. A luminance signal processing unit that modulates a modulated (hereinafter, referred to as FM) luminance signal, and a first high-pass filter (hereinafter, H) that removes unnecessary components from the FM luminance signal.
PF), a band-pass filter (hereinafter, referred to as BPF) for separating a color signal from the video signal, and a color signal processing unit that makes the burst signal of the color signal constant and then emphasizes and converts it into a low frequency band. A second LPF that removes unnecessary components from the low-frequency conversion color signal, a recording unit that adds the FM luminance signal and the low-frequency conversion color signal, amplifies the added signal, and records it on a magnetic tape, and the magnetic tape. Reproducing means for extracting and amplifying the signal recorded in the second reproduction section; second HPF for separating the FM luminance signal from the reproduction signal; FM luminance signal processing means for demodulating the FM luminance signal into a reproduction luminance signal; A third LPF that removes unnecessary components from the luminance signal and a reproduction luminance signal that has been subjected to noise processing from the output are supplied to a second adder, and a fourth LPF that separates the low-frequency conversion color signal from the reproduction signal. LP From the output of the BPF from which the unnecessary component is removed from the frequency-converted reproduction color signal, the reproduction color signal subjected to the necessary reproduction chroma processing by the reproduction chroma processing circuit is the other of the second adder. In a magnetic recording / reproducing apparatus configured to form a reproduced video signal supplied to a first equalizer, a second equalizer, and a third equalizer connected in series for delaying a reproduced color signal in order to improve image quality. First means for producing a color contour signal using the first equalizer input signal and the output signal of the second equalizer; and a color contour using the first equalizer output signal and the third equalizer output signal. Second means for producing an addition signal and third means for producing a luminance contour signal from a reproduction luminance signal
Image quality control means for controlling the addition amount of the color contour addition signal by using the first means and the third means, and adding the color contour addition signal to the output signal of the second equalizer. An improvement device is provided, a secondary LPF and a phase detector are provided, and the phase difference between the two inputs of the phase detector and the phase detector is 90.
At least one filter used for signal processing of the first, second, and third equalizers, the second-order LPF, and the magnetic recording / reproducing apparatus by using the output signal of the phase detector. High-precision filters are integrated by adopting a feedback control configuration.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a video signal processing device according to the present invention.
Is a diagram showing the phase characteristic of the equalizer 11, and FIG.
It is a figure which shows an example of the phase characteristic of the next LPF. The video signal processing device according to the present invention includes an equalizer 11 and a secondary LP.
It is composed of F14, a phase detector 15, and a voltage-current conversion circuit 16. In the block diagram shown in FIG. 1, the color signal A separated from the video signal is input to the equalizer 11.
This equalizer 11 has a color subcarrier f as shown in FIG.
It has a characteristic that the amount of phase delay is 180 degrees in sc. Therefore, the color signal output from the equalizer 11 is a signal delayed for a predetermined time.

A means for automatically adjusting the phase delay amount of the equalizer 11 to obtain a highly accurate characteristic in the video signal processing device having the above-described configuration will be described below. F as shown in FIG.
The color signal A is input to the secondary LPF 14 whose phase delay amount is 90 degrees in sc, and the output of the secondary LPF 14 is detected by the phase detector 15
The output signal of the equalizer 11 is input to the other input C. The output signal of the phase detector 15 is converted into a control current by the voltage-current converter 16, and the output signal of the voltage-current conversion circuit 16 is fed back to the equalizer 11 and the secondary LPF 14, whereby the equalizer 11 is supplied.
Is controlled so that the phase difference between the output signal of 1) and the output signal of the secondary LPF 14 is always 90 degrees, and the equalizer 11 can have desired characteristics. In addition, the voltage-current converter 1
By feeding back the output signal of No. 6 to each filter used in the video signal processing device, it is possible to integrate a filter having highly accurate characteristics.

As described above, according to the present invention, by integrating and automatically adjusting the equalizer, it is possible to obtain highly accurate characteristics in which variations in elements and variations due to temperature changes that occur in the manufacturing process are corrected. Can solve the problem.

[0020]

Embodiments In the video signal processing device having the above-described configuration, when a signal having a low color signal level is input as the color signal, such as a black burst signal (a signal in which no color signal exists other than the burst signal), The phase detector 15 is
Phase detection is performed on the burst signal, but since there is no color signal other than the burst signal, in principle the phase detector 15 does not output a correction signal. However, when the video signal processing device is integrated in an IC, the phase detector 1
Since it is impossible to completely eliminate the offset such as 5,
In a period other than the burst signal period, an offset current is generated and an error occurs.

Therefore, a first embodiment will be described with reference to FIG. 4, in which signals of a constant level are constantly compared to improve the accuracy. The embodiment shown in FIG. 4 is different from the circuit shown in FIG. 1 in that a burst gate pulse generation circuit 24 is added, and the phase detector 1 is output by the output signal of the gate pulse generation circuit 24.
5 is different in that the operation of No. 5 is controlled. In this embodiment, by adding a burst gate pulse generating circuit 24, the phase detector 15 is operated only during the burst period, and feedback control is performed for the equalizer 11, the secondary LPF 14, and each filter used in the video signal processing device. It is configured. The same parts as those of the embodiment shown in FIG.

In the present embodiment, the composite synchronizing signal is supplied to the burst gate pulse generating circuit 24 for separating the burst periods, and the phase detector 15 is operated only during the burst gate pulse period created by the burst gate pulse generating circuit 24. It is configured. With this configuration, the output signal of the secondary LPF 14 and the output signal of the equalizer 11 which the phase detector 15 compares are always burst signals. Therefore, it is possible to eliminate the influence of the offset of the phase detector 15 due to the level of the color signal.

However, when the above embodiment is used in a VTR or the like, the burst waveform is deteriorated because the band of the color signal cannot be sufficiently secured. Further, as the burst gate pulse described above, a highly accurate pulse is required. A second embodiment that solves this problem is shown in FIG. In this example,
The circuit shown in FIG. 1 includes a vertical synchronizing signal separation circuit 25, a switching circuit 26, and a reference signal removing circuit 27, and switches the input signal using the vertical synchronizing signal, and also detects the phase detector 15 and the reference signal removing circuit. The difference is that 27 is operated. The vertical sync signal separated from the composite sync signal is used to switch the color signal and the reference signal, and the phase detector 15 is operated only during the period when the reference signal is selected. The same parts as those of the embodiment shown in FIG.

In this embodiment, the color signal and the reference signal (for example, the color subcarrier fsc) separated from the video signal are input to the switching circuit 26, and the vertical synchronizing signal separated by the vertical synchronizing signal separating circuit 25 is used. In the vertical synchronization period, the switching circuit 26 is controlled so as to select the reference signal. Further, the phase detector 15 is configured to operate only during the vertical synchronization period using the signal generated by the vertical synchronization signal separation circuit 25.
Further, since it is necessary to remove the reference signal added to the color signal during the vertical synchronization period, the reference signal removal circuit 27 is provided at the output of the equalizer 11, and the vertical synchronization signal is generated using the signal created by the vertical synchronization separation circuit 25. During the period, the reference signal removing circuit 27 is operated to remove the reference signal from the color signal. According to this embodiment, it is possible to maintain stable characteristics that are not affected by the offset of the phase detector 15 and the reproduced color signal.

In order to make the equalizer for delaying the color signal of the video signal processing device a more highly accurate characteristic, the third embodiment in which the level variation generated by the integration is automatically adjusted will be described with reference to FIG. Explain. In this embodiment, a variable amplification circuit 31 and a level detection means 34 are added as compared with the video signal processing apparatus shown in FIG. 1, and the output of the level-controlled variable amplification circuit 31 is used as one input of the phase detector 15. The difference is that you did. The same parts as those of the embodiment shown in FIG. Equalizer 1
A variable amplifier circuit 31 is provided at the output of 1, and the level detection means 3
4, the input signal of the equalizer 11 and the variable amplifier circuit 31
The output signals of the level detection means are fed back to the variable amplifier circuit 31, and the input level of the equalizer 11 and the output level of the variable amplifier circuit 31 are controlled to be equal to each other. According to the configuration of the third embodiment, the equalizer 1
The phase comparison circuit 15 absorbs the level variation caused by 1.
To the secondary LPF 14 and the equalizer 11
The input levels from can be equal.

Next, referring to FIG. 7, a fourth embodiment of a video signal processing apparatus which constantly compares signals of a constant level to improve accuracy and eliminates the influence of the color signal of the level detecting means 34. explain. This embodiment is different from the first embodiment shown in FIG. 4 in that a variable amplifier circuit 31 and a level detecting means 34 of the third embodiment shown in FIG. 6 are added, and the first and second embodiments are different. The same parts as those in the third embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the phase detector 15 and the level detector 34 are operated only during the burst gate pulse period. With the configuration of this embodiment, the equalizer 11 compared by the level detection means 34 is compared.
The input signal and the output signal of the variable amplification circuit 31 are always burst signals. Therefore, the level of the equalizer can be corrected with high accuracy without being affected by the reproduced color signal.

Next, since a high precision pulse is required as the burst gate pulse described above, a fifth embodiment which solves this problem is shown in FIG. The embodiment is an application of the third embodiment shown in FIG. 6 to the second embodiment shown in FIG. 5. The color signal and the reference signal are switched, and the level detection means 34 is operated only during the period when the reference signal is selected. It is configured to let. The same parts as those of the embodiment shown in FIGS. 5 and 6 are designated by the same reference numerals, and the description thereof will be omitted. Similar to the embodiment of FIG.
The level detection means 34 is configured to operate only during the vertical synchronization period using the signal created by the vertical synchronization separation circuit 25. With the above configuration, it is possible to maintain stable characteristics that are not affected by the offset of the level detection means 34 and the reproduction color signal.

Next, a sixth embodiment using the present invention in a magnetic recording / reproducing apparatus will be described with reference to FIG. The magnetic recording / reproducing apparatus of this embodiment comprises a video signal recording system and a video signal reproducing system. The video signal recording system is the AGC circuit 7
1, an LPF circuit 72, an emphasis circuit 73, an F
M modulation circuit 74, HPF circuit 75, and BPF circuit 76
A recording chroma processing circuit 77 and a low frequency conversion circuit 7
8, an LPF circuit 79, an adder 80, a recording amplification circuit 81, and a video head 82. The video signal reproduction system includes a video head 84, a reproduction amplification circuit 85,
LPF circuit 86, automatic color level adjustment circuit 87, high frequency conversion circuit 88, reproduction chroma processing circuit 89, video signal processing circuit 100 according to the present invention, HPF circuit 9
0, FM demodulation circuit 91, de-emphasis circuit 92
And an LPF circuit 93, a noise processing circuit 94, and an adder 96.

First, at the time of recording, the luminance signal is separated in the LPF circuit 72 from the video signal in which the level fluctuation is removed by the AGC circuit 71. The separated luminance signal has its high frequency band emphasized by the emphasis circuit 73 and is then supplied to the FM modulation circuit 74 for FM modulation. An unnecessary component is removed from the FM-modulated FM luminance signal by the HPF circuit 75, and the result is supplied to the adder 80. In addition, at the time of recording, a of the switching circuit 90
The color signal is separated in the BPF circuit 76 from the video signal passing through the contact. The recording chroma processing circuit 77 removes level fluctuations from the separated color signals, performs necessary chroma processing, and then low-frequency converts it by a frequency low-frequency conversion circuit 78. The LPF circuit 79 removes unnecessary components generated by the low-frequency conversion from the low-frequency converted color signal and supplies the color signal to the other of the adder 80. In the adder 80, the FM luminance signal and the low-frequency converted color signal are frequency-multiplexed and recorded on the magnetic tape 83 via the recording / amplifying circuit 81 and the video head 82.

During reproduction, the signal reproduced through the video head 84 is amplified by the reproduction amplifier circuit 85. Next, an FM luminance signal is extracted in the HPF circuit 90, the extracted FM luminance signal is demodulated to a baseband luminance signal in the FM demodulation circuit 91, de-emphasized in the de-emphasis circuit 92, and further the LPF circuit. 93
The unnecessary components are removed in step (1), noise removal processing is performed in the noise processing circuit 94, and then the signal is supplied to the adder 96. Further, the low-pass conversion color signal is separated from the reproduction signal by the LPF circuit 86, the level fluctuation is removed by the automatic color level adjusting circuit 87, and converted into the reproduction color signal by the frequency high-pass conversion circuit 88. The reproduction color signal is passed through the b contact of the switching circuit 90 to remove unnecessary components generated at the frequency conversion in the BPF circuit 76, and the reproduction chroma signal processing circuit 89.
After being subjected to the necessary processing in (1), it is supplied to the color signal delay section 100 which is composed of the video signal processing circuit of the present invention. The reproduced color signal delayed by the color signal delay unit 100 is supplied to the adder 96. In the adder 96, the reproduced color signal and the luminance signal are added together to form a reproduced video signal.

In this embodiment, the color signal delay section 100 described in the embodiment of FIG. 1 is provided with a terminal 101 for automatic filter adjustment, and various control signals required for signal processing of the magnetic recording / reproducing apparatus are provided using this control signal. Filter, LPF circuits 72, 79, 86, 93 in this embodiment, HPF circuits 75, 90, BP
By controlling each filter used in the F circuit 76, all the filters can be automatically adjusted.

Color signal delay unit 100 shown in this embodiment
Is not limited to the video signal processing circuit shown in FIG.
It goes without saying that any type of video signal processing circuit shown in FIG. 8 can be applied.

Next, the seventh embodiment in which the present invention is applied to an image quality improving circuit.
An example will be described. FIG. 10 is a block diagram showing an embodiment of an image quality improving circuit using the video signal processing device according to the present invention. The image quality improving circuit of this embodiment includes equalizers 11, 12 and 13 connected in series and a secondary LPF circuit 14.
, Phase detector 15, voltage-current conversion circuit 16, subtractors 17, 18, luminance contour signal generation circuit 19, color contour signal generation circuit 20, comparison means 21, multiplier 22, and adder 23. The output signal of the equalizer 12 in the second stage is input to one input of the phase detector 15. In this embodiment, the second-order LPF circuit 14 has the phase characteristic shown in FIG. 3 already described. Further, the output signal B of the secondary LPF circuit 14 input to the phase detector 15 and the output signal C of the equalizer 12 have the vector relationship shown in FIG. That is, the output signal C of the equalizer 12 is delayed by 360 ° from the color signal A, and the secondary LPF circuit 1
Since the output signal B of No. 4 is delayed from the color signal A by 90 °, the output signal B and the output signal C are different from each other by 90 °.

The color signal separated from the video signal is equalized by the equalizers 1 of the equalizers 11, 12 and 13 connected in series.
Input to 1. The equalizers 11, 12, 13 are
As shown in FIG. 2, the phase delay amount is 180 at fsc.
It has a certain degree of characteristics. Therefore, the subtractor 1 subtracts the output signal C of the equalizer 12 from the input signal A of the equalizer 11.
By subtracting at 7, the contour signal component of the color signal is created, and using this color contour signal component, the color contour signal creation circuit 2
At 0, a color contour signal is created. Similarly, a brightness contour signal is created in the brightness contour signal creation circuit 19 for the brightness signal. The comparing means 21 compares both the luminance contour signal and the color contour signal, and supplies an output signal for determining the addition amount of the color contour signal to the multiplier 22. The other input of the multiplier 22 is fed from the input signal of the equalizer 12 to the equalizer 13
A color contour addition signal obtained by subtracting the output signal of 1 by the subtractor 18 is supplied. The signal obtained by calculating the two input signals by the multiplier 22 becomes the color contour signal. Equalizer 1 which is the main color signal
The color contour signal can be obtained by adding the color contour signal to the output signal of No. 2 in the adder 23.

In the image quality improving circuit using the video signal processing device having the above-described structure, the equalizers 11, 12, 1 are used to generate the color contour signal and the color contour addition signal.
As the characteristic of No. 3, a highly accurate phase delay amount is required. Therefore, the color signal is input to the secondary LPF circuit 14 having a phase delay amount of 90 degrees at fsc as shown in FIG.
The output of the circuit 14 is connected to one input of the phase detector 15, and the output of the equalizer 12 is input to the other input.

FIG. 11 shows a vector diagram of the two input signals, the vector of the color signal is A, and the output of the secondary LPF circuit 14 is delayed by 90 degrees from the color signal, as can be seen from the characteristics of FIG. The output of the second equalizer is a signal C that is passed through two equalizers whose phase is delayed by 180 degrees at fsc and is delayed by 360 degrees from the color signal, as shown in the characteristic of FIG. The output signal of the phase detector 15 is converted into a control current in the voltage-current converter 16, and the output signal of the voltage-current converter circuit 16 is equalized.
The output signal of the equalizer 12 and the secondary LPF circuit 14 are fed back to the secondary LPF circuit 14,
Is controlled so that the phase difference between the output signals is always 90 degrees, and the equalizers 11, 12, and 13 can have desired characteristics.

As described above, according to the present invention, by integrating and automatically adjusting the equalizer, it is possible to obtain highly accurate characteristics in which variations in elements and variations due to temperature changes that occur in the manufacturing process are corrected. Can solve the problem.

Next, similar to the first embodiment shown in FIG. 4, a constant level signal is constantly compared without improving the accuracy due to the offset of the phase detector 15 used in the image quality improving apparatus. Example 8 will be described with reference to FIG. In this embodiment, a burst gate pulse generation circuit 24 for generating a burst gate pulse from the composite sync signal of the first embodiment shown in FIG. 4 is further added to the video signal processing device of the seventh embodiment shown in FIG. The phase detector 15 is provided only during the burst period, and the equalizer and 2
The next LPF circuit is configured to perform feedback control. The same parts as those in the embodiment shown in FIGS. 4 and 10 are designated by the same reference numerals,
The description is omitted.

In this embodiment, the burst gate pulse generation circuit 24 for separating the burst period by the composite synchronizing signal.
And the phase detector 15 is operated only during the burst gate pulse period generated by the burst gate pulse generation circuit 24. According to this configuration, the output signal of the secondary LPF circuit 14 and the output signal of the equalizer 12 which the phase detector 15 compares are always burst signals. As a result, it is possible to eliminate the influence of the offset of the phase detector 15 due to the change in the level of the color signal.

However, as described in the embodiment of FIG. 5, when the embodiment shown in FIG. 12 is used in a VTR or the like,
Since the band of the color signal cannot be sufficiently secured, the burst waveform is deteriorated. Further, as the burst gate pulse described above, a highly accurate pulse is required. FIG. 13 shows a ninth embodiment which solves this problem. This example
The second embodiment shown in FIG. 5 is applied to the seventh embodiment shown in FIG. 10. The color signal and the reference signal are switched, and the phase detector 15 is operated only during the period when the reference signal is selected. It is configured. The same parts as those of the embodiment shown in FIGS. 5 and 10 are designated by the same reference numerals, and the description thereof will be omitted.

The color signal and the reference signal (for example, fsc) separated from the video signal are input to the switching circuit 26, and the signal of the vertical synchronization separation circuit 25 is used to select the reference signal during the vertical synchronization period. 26 are controlled. Also,
The phase detector 15 is operated only during the vertical synchronization period by using the signal generated by the vertical synchronization separation circuit 25.
Further, since the added reference signal needs to be removed, the reference signal removing circuit 27 is provided at the output of the equalizer 12, and the signal created by the vertical sync separation circuit 25 is used for removal. As described above, it is possible to maintain stable characteristics that are not affected by the offset of the phase detector 15 and the reproduced color signal.

The operating state of each node of the embodiment shown in FIG. 13 is shown in FIG. The vertical synchronizing period signal in FIG. 13 is D, and the switching circuit 26 operates to select the reference signal only during the period when D is'H '. Therefore, the output signal A of the switching circuit 26 is a color signal and a color subcarrier signal. It becomes the added signal. The output signal A of the switching signal 26 becomes a signal B whose phase is delayed by 90 degrees in the secondary LPF 14 and a signal C which is delayed by 360 degrees in the equalizers 11 and 12, and the signal B,
The phase difference of C is detected by the phase detector 15. It is clear from FIG. 11 that the signals B and C detected are always at stable levels.

The equalizer for delaying the color signal of the video signal processing device requires the highly accurate phase characteristic as described above, but at the same time the highly accurate level characteristic is also required. Therefore, a tenth embodiment in which the level variation generated by integrating the equalizers is automatically adjusted will be described with reference to FIG. FIG. 15 applies the third embodiment shown in FIG. 6 to the seventh embodiment shown in FIG. 10, and shows the level detection means for equalizing the characteristics of the equalizers 11, 12, and 13. This is an example. The same parts as those of the embodiment shown in FIGS. 6 and 10 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, the variable amplifier circuits 31, 3 are connected to the outputs of the equalizers 11, 12, 13 connected in series.
2, 33 are provided. Since the equalizers 11, 12, 13 are formed on the same substrate, they have the same characteristics,
The variations in output level are also equal. Therefore, the level detection means 34 compares the levels of the input signal of the equalizer 11 and the output signal of the variable amplification circuit 33, and the output signal of the level detection means is fed back to the variable amplification circuits 31, 32, 33, and 1
Control is performed so that the input level of the equalizer 11 in the third stage and the output level of the variable amplifier circuit 33 in the third stage become equal. With this configuration, level variations due to the equalizers 11, 12, 13 can be absorbed.

An eleventh embodiment of the video signal processing apparatus for eliminating the influence of the color signal by the level detecting means 34 will be described with reference to FIG. This is an example in which the fourth embodiment shown in FIG. 7 is applied to the tenth embodiment shown in FIG.
The same parts as those in FIGS. 7 and 15 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, the burst gate pulse generation circuit 2
The level detection means 34 is operated only during the burst gate pulse period created in 4. With this configuration, the input signal of the equalizer 11 and the output signal of the variable amplification circuit 33, which the level detection means 34 compares, are always burst signals. Therefore, the level of the equalizer can be corrected with high accuracy without being affected by the reproduced color signal.

Further, since a high precision pulse is required as the burst gate pulse described above, a twelfth embodiment which solves this problem is shown in FIG. This example
This is an example in which the fifth embodiment of FIG. 8 is applied to the ninth embodiment of FIG. 13, and the level detection means 34 is operated only during the period when the color signal and the reference signal are switched and the reference signal is selected. The same parts as those of the embodiment shown in FIGS. 8 and 13 are designated by the same reference numerals, and the description thereof will be omitted. The color signal and the reference signal separated from the video signal are input to the switching circuit 26, and the signal of the vertical synchronizing separation circuit 25 is used to control the switching circuit 26 to select the reference signal during the vertical synchronizing period. Further, the level detection means 34 is operated only during the vertical synchronization period using the signal generated by the vertical synchronization separation circuit 25. As described above, it is possible to maintain stable characteristics that are not affected by the offset of the level detection means 34 and the reproduction color signal.

The tenth to twelfth shown in FIGS.
This embodiment is suitable for a configuration in which the equalizers that are continuously connected have the same characteristics, but the thirteenth and fourteenth embodiments that use equalizers having different characteristics will be described with reference to FIGS. 18 and 19. To do. FIG. 18 shows a thirteenth embodiment of the level detection means when the equalizers 12 and 13 have the same characteristic and only the equalizer 11 has a characteristic different from the others. In this embodiment, the outputs of the equalizers 11, 12, 13 connected in series are connected to the variable amplifier circuits 3 respectively.
1, 32, and 33 are provided to equalize the input of the first-stage equalizer 11 and the output of the first-stage variable amplifier circuit 31, and the input of the second-stage equalizer 12 and the third-stage variable amplifier circuit 33. The output is made equal. The first level detecting means 35 compares the levels of the input signal of the first-stage equalizer 11 and the output signal of the first-stage variable amplifier circuit 31, and feeds back the output signal of the level detecting means 35 to the variable amplifier circuit 31. Then, the input level of the equalizer 11 and the output level of the variable amplifier circuit 31 are controlled to be equal.
On the other hand, since the equalizers 12 and 13 have the same characteristics, the second level detection means 36 causes the equalizers 12 of the second stage to operate.
Of the output signal of the third stage variable amplifier circuit 33 is compared, and the output signal of the level detection means 36 is fed back to the variable amplifier circuits 32 and 33 to equalize the second stage equalizer 12.
The input level is controlled to be equal to the output level of the variable amplification circuit 33 in the third stage. With the above configuration, level variations due to the equalizers 11, 12, 13 can be absorbed.

FIG. 19 shows a fourteenth embodiment in which all the equalizers have different characteristics. Each equalizer 11,1
Variable amplifier circuit 3 connected to inputs 2 and 13 and its output
Level detection means 3 is provided to the outputs of 1, 32 and 33, respectively.
5, 37, 38 are provided. The level of the input signal of each equalizer and the level of the output signal of the variable amplifier circuit at the subsequent stage of this equalizer are compared by the corresponding level detection means, the output signal of the level detection means is fed back to the variable amplification circuit, and the two level detection means are connected. By controlling the inputs to be equal,
It is possible to absorb the level variation of each equalizer.

An example of the structure of the level detection means used in the embodiments shown in FIGS. 6 to 8 and 15 to 19 is shown in FIG.
It shows in 0. The level detecting means includes a subtractor 39 and a multiplier 4
It consists of 0 and 41. The first input signal is squared by the first multiplier 40, the second input signal is similarly squared by the second multiplier 41, and the result of calculating the two signals by the subtractor 39 is used as the output signal. To do. With this configuration, the correction signal is not output when the levels of the two input signals are equal,
Only when the two input levels are different, a control signal corresponding to the input level difference is obtained, and the level can be automatically adjusted.

Next, a fifteenth embodiment in which the present invention is applied to a magnetic recording / reproducing apparatus having an image quality improving apparatus will be described with reference to FIG. This embodiment is an example in which the seventh embodiment shown in FIG. 10 is applied to the sixth embodiment shown in FIG. In this embodiment, the video signal processing circuit 100 of the magnetic recording / reproducing apparatus shown in FIG. 9 is used as the image quality improving unit 20 of the seventh embodiment of FIG.
It is different from the sixth embodiment in that it is set to 0 and a luminance signal delay circuit 95 is added. The same parts as those of the embodiment shown in FIGS. 9 and 10 are designated by the same reference numerals, and the description thereof will be omitted. The signal reproduced through the video head 84 is amplified by the reproduction amplifier circuit 85. The FM luminance signal is extracted by the HPF 90, demodulated to a baseband luminance signal by the FM demodulation circuit 91, de-emphasized by the de-emphasis circuit 92, unnecessary components are removed by the LPF 93, and processed by the noise processing circuit 94. The luminance signal is supplied to the adder 96 via the luminance signal delay circuit 95 that compensates the delay time of the reproduction color signal generated in the equalizers 11 and 12 of the image quality improving unit 200. Further, the low-frequency conversion color signal is separated from the reproduction signal by the LPF 86, and the automatic color level adjusting circuit 8
7. The level fluctuation is removed by 7, and the high frequency conversion circuit 88
After it is converted into a reproduced color signal by the B contact of the switching circuit 90, the BPF 76 removes unnecessary components generated during the frequency conversion from the reproduced color signal, and after the necessary processing is performed by the reproduced chroma signal processing circuit 89. , And is supplied to the image quality improvement unit 200. The reproduced color signal improved by the image quality improving unit 200 is supplied to the adder 96. The reproduction color signal and the luminance signal are added by the adder 96 to form a reproduction video signal.

In this embodiment, a terminal 201 for automatic filter adjustment is provided in the image quality improving section 200 described in the embodiment of FIG. 10, and various filters necessary for signal processing of the magnetic recording / reproducing apparatus are provided by using this control signal. In this embodiment, the LPF circuits 72, 79, 86, 93, HPF circuits 75, 90, BP
By controlling the filters used in the F circuit 76 and the luminance signal delay circuit 95, all the filters can be automatically adjusted.

It goes without saying that the image quality improving section 200 shown in this embodiment can be applied to any of the formats shown in FIGS. 8 and 12 to 16.

The two inputs of the phase detector 15 used in all of the above-mentioned embodiments may have any structure as long as the phase difference is 90 degrees as shown in FIGS. That is, in the example of FIG. 22, the color signal is directly input to one input of the phase detector 15, and the equalizer 11 and the equalizer 11 are input to the other input.
A signal that has passed through 12 and then passed through the secondary LPF 14 is input, and the two signals are 90 ° out of phase with each other. In the example of FIG. 23, the color signal is directly input to one input of the phase detector 15, and the equalizer 1 is input to the other input.
The signal that has passed through 1, 12, 13 and then through the secondary LPF 14 is input, and the two input signals are 90 ° out of phase with each other. Furthermore, the example of FIG.
The color signal that has passed through the secondary LPF 14 is input to one of the inputs 5 and the color signal that has passed through the equalizers 11, 12, 13 is input to the other input, and the two input signals are 90 ° out of phase with each other. ing.

Next, as the video signal system, NTSC system or P
There are systems such as the AL system, and a 16th embodiment corresponding to these systems will be described with reference to FIG. In order to make the video signal processing device compatible with each of these modes, the voltage-current converter 16 corresponding to the characteristics of the first signal system and the voltage-current converter 28 corresponding to the second signal system are provided in the phase detector 15. A switching circuit 29 that switches the output signals of the first and second voltage-current converters is provided at the output. Then, the switching circuit 29 is controlled by the mode switching signal, and the equalizer 11,
Feedback control of the 12th, 13th, and second-order LPF circuits 14 enables automatic adjustment of filters corresponding to each mode. The sixteenth embodiment shown in FIG. 25 is shown in FIGS.
It goes without saying that the same can be applied to all the embodiments shown in FIG.

The phase detector 15 used in the above-mentioned video signal processing device is controlled so that the phase difference between the two input signals becomes 90 degrees, and the first input signal and the second input signal are fsc.
The number of configurations in which the phase difference of the input signals of 1 shifts 90 degrees is not limited to one. An example thereof is shown in FIG. Phase is 180 at fsc
The phase difference between the output signal A of the equalizer delayed by 90 degrees and the output signal C of the secondary LPF similarly delayed by 90 degrees at fsc is 90 degrees as indicated by the phase lock point 1. In feedback controlling the equalizer and the second-order LPF by using the above-mentioned two inputs, if the control range of the phase delay amount of each filter is set wide, the following problems occur. When a highly sensitive phase detector is used, or in an unstable state at the start of detection, the output signal from the phase detector 15 is excessively supplied. Therefore, the equalizer fs is proportionally increased.
The amount of phase delay at c also increases. Then, as shown in FIG. 28, when the phase delay amount becomes close to 360 degrees at fsc, the phase difference from the second-order LPF circuit 14 becomes close to 90 degrees, and the equalizer automatically operates at the phase lock point 2 different from the desired characteristic. It will be adjusted. This state is called pseudo lock.

FIG. 27 shows an example of the voltage-current converter used in the phase detector 15 provided with a measure against pseudo lock. This voltage-current converter has resistors 51, 52, 53, 54, 55, 6
3, 67, PNP transistors (hereinafter, referred to as PNPTr) 57, 58, 59, 60, and NPN transistors (hereinafter, referred to as NPNTr) 61, 62, 65, 66
, Power supply Vcc56, constant current source 68 and reference current source 69
Composed of and.

This voltage-current converter has a resistor 51, one of which is connected to Vcc and the other of which is connected to the emitter of the PNPTr 57.
A resistor 52, one of which is Vcc and the other of which is connected to the emitter of PNPTr 58, the base and collector of PNPTr 57 and the base of PNPTr 58 are connected to form a current mirror, and the base, collector and PN of PNPTr 57 are connected.
The connection point of the base of the PTr58 is the collector of the NPNTr62, one of the resistors 63 is the emitter and NP is the base.
The emitter of NTr61 is Darlington connected.
The collector of the NPNTr 61 is supplied with Vcc, and the base is supplied with the phase detection voltage. Similarly, the collector of the NPNTr66 is the collector of the NPNTr66, and the resistor 67 is the emitter.
One of them has a base to which the emitter of the NPNTr65 is connected in Darlington. The collector of NPNTr65 is supplied with Vcc, and the base is supplied with a reference voltage. Resistor 63,
The other of 67 is connected to a current source. NPNTr66
, PNPTr58 collector, PNPTr59 collector and reference current source 69 are connected, and the base is PNPTr
One of the resistor 54 and the base of the resistor 54, one of the resistors 53 for the emitter, and the resistor 5 for the emitter of the PNPTr60.
One of the resistors 5, 53, 54 and 55 is connected to Vcc to form a current mirror.

In the voltage-current converter configured as described above, if the current value at which the phase difference between the two input signals of the phase detector 15 changes by ± 90 degrees with respect to the current value of the reference current source 69 is ΔI, the correction current is The current value I of a certain constant current source 68 is I <ΔI
Set to a relationship. FIG. 28 is a vector diagram showing the state at that time. Since this voltage-current converter considers only the variation amount due to the integration in the control range of the phase delay amount, when the total correction current I is added to and subtracted from the reference current, it is possible to reach the vicinity of the phase lock point 2. The amount of phase delay does not change. According to the above configuration, pseudo lock can be prevented and a desired filter can be automatically adjusted. It goes without saying that the voltage-current converter shown in FIG. 27 can be applied to all the embodiments of the video signal processing devices shown in FIGS.

[0058]

As described above, according to the present invention,
The external block filter used to delay the conventional color signal is provided with a secondary LPF and a phase detector to perform feedback control, whereby integration can be achieved, and variation in characteristics due to integration and variation in characteristics due to temperature change can be achieved. A highly accurate video signal processing device in which Therefore, IC
Since no external adjustment is required and the substrate area can be reduced, the cost can be reduced.

Further, according to the present invention, as a period for operating the phase detector, only the burst period in which a constant signal always exists is operated, so that it does not depend on the color signal and is highly accurate at low cost. A video signal processing device is obtained.

Further, according to the present invention, the input of the video signal processing device is switched between the color signal and the reference signal, and the phase detector is operated in synchronization with the input of the reference signal. By doing so, it is possible to obtain a highly accurate video signal processing device that does not completely depend on color signals.

According to the present invention, a variable amplifier circuit is provided at the output of each equalizer of the video signal processing apparatus, and the input signal of the equalizer and the output signal of the variable amplifier circuit are compared by the level detection means and feedback control is performed. It is possible to obtain a more highly accurate video signal processing device in which the output level variation of each equalizer is automatically adjusted.

Further, according to the present invention, a magnetic recording / reproducing apparatus having highly accurate characteristics can be obtained by controlling each filter used in the magnetic recording / reproducing apparatus by the control signal of the video signal processing apparatus.

In addition, by having two or more control signals for the video signal processing device, a highly accurate video signal processing device compatible with each signal system such as the NTSC system and the PAL system can be obtained.

By setting a limit on the control signal of the video signal processing device, a highly accurate video signal processing device capable of controlling stable characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a video signal processing apparatus showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing phase characteristics of an equalizer according to the present invention.

FIG. 3 is a characteristic diagram showing phase characteristics of a secondary LPF according to the present invention.

FIG. 4 is a block diagram of a video signal processing device showing the first embodiment of the present invention.

FIG. 5 is a block diagram of a video signal processing device showing a second embodiment of the present invention.

FIG. 6 is a block diagram of a video signal processing device showing a third embodiment of the present invention.

FIG. 7 is a block diagram of a video signal processing device showing a fourth embodiment of the present invention.

FIG. 8 is a block diagram of a video signal processing device showing a fifth embodiment of the present invention.

FIG. 9 is a block diagram of a video signal processing device showing a sixth embodiment of the present invention.

FIG. 10 is a block diagram of a video signal processing device showing a seventh embodiment of the present invention.

11 is a vector diagram of the phase control shown in FIG.

FIG. 12 is a block diagram of a video signal processing device showing an eighth embodiment of the present invention.

FIG. 13 is a block diagram of a video signal processing device showing a ninth embodiment of the present invention.

FIG. 14 is a waveform diagram of each point shown in FIG.

FIG. 15 is a block diagram showing a configuration example of a video signal processing device according to a tenth embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration example of a video signal processing device according to an eleventh embodiment of the present invention.

FIG. 17 is a block diagram showing a configuration example of a video signal processing device according to a twelfth embodiment of the present invention.

FIG. 18 is a block diagram showing a configuration example of a video signal processing device according to a thirteenth embodiment of the present invention.

FIG. 19 is a block diagram showing a configuration example of a video signal processing device according to a fourteenth embodiment of the present invention.

FIG. 20 is a block diagram showing a configuration example of a level detecting means according to the present invention.

FIG. 21 is a block diagram showing a configuration example of a video signal processing device according to a fifteenth embodiment of the present invention.

FIG. 22 is a block diagram showing a configuration example (1) of a phase detector according to the present invention.

FIG. 23 is a block diagram showing a configuration example (No. 2) of the phase detector according to the present invention.

FIG. 24 is a block diagram showing a configuration example (No. 3) of the phase detector according to the present invention.

FIG. 25 is a block diagram showing a configuration example of a video signal processing device capable of mode switching according to a sixteenth embodiment of the present invention.

FIG. 26 is a characteristic diagram showing a phase characteristic of an input signal of the phase detector according to the present invention.

FIG. 27 is a circuit diagram showing a configuration of a voltage-current converter according to the present invention.

FIG. 28 is a vector diagram of an input signal of the phase detector according to the present invention.

[Explanation of symbols]

11, 12, 13 Equalizer 14 Second LPF 15 Phase detector 16, 28 Voltage-current conversion circuit 17,18,39 Subtractor 19 Luminance contour signal creation circuit 20 color contour signal generation circuit 21 Comparison means 22, 40, 41 Multiplier 23,80,96 adder 24 Burst gate pulse generator 25 Vertical sync separation circuit 26,90 switching circuit 27 Reference signal removal circuit 31, 32, 33 variable amplifier circuit 34, 35, 36, 37, 38 Level detection means 51, 52, 53, 54, 55, 63, 67 Resistance 57,58,59,60 PNP transistor 61, 62, 65, 66 NPN transistor 64 batteries 71 AGC circuit 72, 79, 86, 93 LPF 73 Emphasis circuit 74 FM modulation circuit 75,90 HPF 76 BPF 77 Recording chroma processing circuit 78 Frequency conversion circuit 81 recording amplifier 82,84 video heads 83 magnetic tape 85 Regenerative amplifier 87 Automatic color level adjustment circuit 88 high frequency conversion circuit 89 Playback chroma processing circuit 91 FM demodulation circuit 92 De-emphasis circuit 94 Noise processing circuit 95 Luminance signal delay circuit 100 color signal delay circuit 200 Image quality improvement section 201 Filter automatic adjustment terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akifumi Tabata 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Hitachi Image Information Systems, Inc. (72) Inventor Hiroyuki Hori 1410, Inada, Hitachinaka, Ibaraki Hitachi, Ltd. Video Information Media Business Department (72) Inventor Akira Okasaka 5-20-1 Kamimizuhoncho, Kodaira-shi, Tokyo Hitachi, Ltd. Semiconductor Business Department (72) Inventor Masahiro Sasaki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Co., Ltd. Hitachi Image Information System (72) Inventor Kazuki Ito 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan, Victor Company of Japan (56) Reference JP-A-5-67944 (JP, A) JP-A-8- 111630 (JP, A) JP-A-7-212186 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 9/44-9/898

Claims (13)

(57) [Claims] 1. A video signal processing device for separating a video signal into a luminance signal and a chrominance signal for signal processing, an equalizer for delaying the color signal, a secondary low-pass filter for delaying the color signal, and the equalizer. And a phase detector to which the output of the second-order low-pass filter is input, and the phase difference between the two inputs of the phase detector is set to 90 degrees, and the output signal of the phase detector is set. A video signal processing device, characterized in that the phase delay amount of the equalizer and the second-order low-pass filter is automatically adjusted by feedback-controlling the equalizer and the second-order low-pass filter. 2. A first serially connected equalizer of the equalizers.
A first color contour signal creating means for creating a color contour signal by using the input signal of the first equalizer and the output signal of the second equalizer, and the first and second equalizers, and the second and third equalizers. A second color contour signal creating means for creating a color contour addition signal using the output signal of the first equalizer and the output signal of the third equalizer; and a luminance contour signal from a luminance signal separated from the video signal. And a comparison means for comparing the output of the first color contour signal creating means with the output of the luminance contour signal creating means, and the comparison with the output of the second color contour signal creating means. Multiplication means for multiplying the output of the means to generate a color contour addition signal; and addition means for adding the color contour addition signal to the output signal of the second equalizer to obtain a contour emphasis color signal. Video signal processing apparatus according to claim 1, wherein provided. 3. A variable detection circuit is connected to the output of the equalizer, and level detection means for comparing the level of the input signal of the equalizer and the level of the output signal of the variable amplification circuit is provided, and the output of the amplified equalizer. Is set as a part of the input signal of the phase detector, and the variable amplifier circuit is feedback-controlled by using the output signal of the level detecting means to automatically adjust the variation of the output level of the equalizer. Video signal processing device. 4. The first, second, and third variable amplifier circuits are respectively connected to the outputs of the first, second, and third equalizers, and the level of the input signal of the first equalizer and the third equalizer are connected. A level detection means for comparing the levels of the output signals of the variable amplifier circuits is provided, and the output of the amplified equalizer is used as a part of the input signal of the phase detector, and the output signal of the level detection means is used to change the level. 3. The video signal processing device according to claim 2, wherein the amplifier circuit is feedback-controlled to automatically adjust variations in the output level of the equalizer. 5. The video signal processing device according to claim 1, wherein at least one filter used in the video signal processing device is feedback-controlled by using an output signal of the phase detector. . 6. A video signal processing device according to claim 1, wherein a circuit for extracting a burst signal from the composite synchronizing signal is provided, and the phase detector is operated in synchronization with the burst period. . 7. The video signal processing device according to claim 1, wherein the phase detector is operated during a vertical synchronization period. 8. The video signal processing device according to claim 1, wherein a reference signal is mixed with the color signal, and the phase detector is operated in synchronization with the reference signal. 9. A reference signal removing circuit for removing a reference signal from the output of the equalizer, and the reference signal removing circuit is operated in synchronization with the reference signal.
The described video signal processing device. 10. The video signal processing device according to claim 8, wherein a color subcarrier is used for the reference signal. 11. The video signal processing device according to claim 3, wherein the level detection means includes at least two multipliers and one subtractor. 12. The video signal according to claim 1, wherein the means for feedback controlling the equalizer and the second-order low-pass filter has a configuration capable of controlling two or more characteristics by a mode switching signal. Processing equipment. 13. The method according to claim 1, wherein the means for feedback controlling the equalizer and the second-order low pass filter is set so that the phase difference between the two inputs of the phase detector cannot be changed by 90 ± 90 degrees or more. Any one of the video signal processing devices.